Capillary fiber bundles

ABSTRACT

Capillary fiber bundles of semipermeable membrane material may be used by winding the fibers onto a reel member to form an annular assembly of the fibers, and thereafter cutting the annular assembly into separate bundles. In accordance with this invention, the capillary tubing is fed to the reel through guide slot means elongated in a direction generally parallel to the axis of rotation of the reel. The tension on the capillary tubing is sufficiently low to allow the capillary tubing to move about while winding in the guide slot means in generally random manner. Accordingly, the bundles comprise strands in generally non-parallel crossing arrangement with adjacent strands. Individual bundles may be wrapped in a special flexible sheet, and cut at their ends for improved quality.

This is a division of application Ser. No. 041,112, filed May 21, 1979,now U.S. Pat. No. 4,276,687.

BACKGROUND OF THE INVENTION

In U.S. applications Ser. No. 658,143, filed Feb. 13, 1976, now U.S.Pat. No. 4,226,378, and Ser. No. 767,711, filed Feb. 11, 1977, nowabandoned, a winding apparatus for tubular capillary fibers is shown.The fibers are wound on a reel to create a circular bundle of the woundfibers, which bundle is then enclosed in a "clam shell" type rigidtemporary housing, with the individual enclosed bundles being then cutaway from the fibrous bundle loop. A reciprocating arm guides the fibersback and forth across the width of the bundle as they are wound onto thebundle, for improvement of the dialysis characteristics of dialyzersmade with the fiber bundles.

In this invention, a tubular hollow fiber bundle can be prepared whichhas improved advantages of manufacture and performance as a dialyzer.The rate of defective bundles which are produced is substantially lessthan in prior art techniques, while improved performance of the dialyzeris also noted after installation of the completed bundle into a housingto form a dialyzer, particularly the dialyzer for blood. In particular,improved performance can be obtained for several reasons, including theimproved, smooth cut of the ends of the bundle which are provided inaccordance with this invention.

DESCRIPTION OF THE INVENTION

In this invention, bundles of tubular capillary fibers of semi-permeablemembrane material for use in a membrane diffusion device may be providedby winding the capillary fibers onto a reel member to form an annularassembly of the fibers. Thereafter, the annular assembly may be cut intoseparate bundles.

In accordance with this invention, the capillary fibers are fed to thereel, typically off of spools, through guide slot means elongated in adirection generally parallel to the axis of rotation of the reel, and ata tension on the capillary fibers sufficiently low to allow thecapillary fibers to move about while winding in the guide slot means ingenerally random manner.

As a result of this, the bundles comprise fibers in generallynon-parallel, crossing arrangement with adjacent fibers.

Typically, the guide slot means is of essentially the width of the reelmember and the annular assembly of fibers so that the generally randomdeposition of the fibers onto the bundle extends from side to sidethereof.

It is also preferred to simultaneously wind a plurality of strands ofcapillary fibers from spools onto the reel member through a plurality ofguide slots of the guide slot means.

Prior to the cutting step, it is preferable for the bundles to bewrapped in a flexible sheet which is typically paper. Thereafter, thebundles are cut through the wrapped paper sheet to obtain an improvedcut of the bundle ends.

A specific wrapped paper sheet which may be used defines an inner endportion, positioned against the bundle, which is of rectilinear shape.An outer end portion of the paper sheet, opposed to the inner endportion, defines sides which taper inwardly towards the outer end, sothat the sheet may be of the shape of an asymmetric hexagon having twoadjacent 90° corners.

Marker means are provided on the paper sheet, spaced from the middle ofthe sheet toward the outer end. Accordingly, the compression of thewrapped bundle to the paper sheet may be predetermined by placing, inthe wrapping process, the outer end of the wrapped sheet on the markermeans, to predetermine and control the amount of compressive pressure onthe bundle.

The tapering ends of the paper sheet facilitate twisting while wrappingof the paper sheet around the bundle, to obtain the desired,predetermined compression.

Referring to the drawings,

FIG. 1 is a perspective view of the winding apparatus used in accordancewith this invention.

FIG. 2 is a fragmentary, perspective view of the reel-finding mechanism,showing the guide slot means.

FIG. 3 is a perspective view of the reel mechanism used herein afterwinding, with portions broken away for purposes of clarity andconvenience, with the reel being removed from its hub and positionedhorizontally, and with one portion of the annular assembly of fibersbeing wrapped with the flexible sheet as described herein.

FIG. 4 is a plan view of one embodiment of the flexible sheet used inthis invention.

FIG. 5 is a fragmentary, perspective view showing the flexible sheet iswound condition about the annular assembly of fibers.

FIG. 6 is a fragmentary perspective view showing the step of cutting theends of the bundle through lateral portions of the flexible sheet.

FIG. 7 is a perspective view of a dialyzer comprising a housing which,in turn, contains the bundle of this invention.

Referring to the drawings, the bundles of this invention may be made bywinding tubular capillary fibers 10, made, for example, ofCuprophan-type cellulose, off of a series of spools 12 onto a reelmember 14, which comprises in the specific embodiment thirteen forkmembers 16 mounted on the periphery of reel 14, for receiving the fibersand holding them as an annular assembly 18 of capillary fibers isformed.

The plurality of fibers 10 each pass through guide slot means 20 carriedby bracket 21 and comprising a plurality of guide slots 22, which can beseen to be each elongated in the direction which is generally parallelto the axis of rotation 24 of reel 14. Spools 12 of capillary fibermaterial may simply rest loosely on spindles 26 if desired, so thatthere is essentially no drag or tension on the capillary fibers 10 asthey are paid off of the spools 12 and wound onto reel 14. As a resultof this, as the reel can briskly rotate at a rate of preferably 100 to200 rpm., and specifically 160 rpm., the spools 12 carrying fibers 10freely unwind, causing the fibers 10 to move about or oscillate, whilerunning through the guide slots 22, in a generally random manner. As aresult of this, the annular assembly of fibers 18, and accordingly, thebundles ultimately formed therefrom, comprise fibers in generallynon-parallel, crossing arrangement with adjacent fibers.

Preferably, guide slots 22 are of essentially the width of the reelmember 14 and the annular assembly 18 being formed thereon. The width ofrecesses 28 in forks 16 also generally corresponds to this dimension.

After the winding step has taken place, reel 14 may be removed fromrotary hub member 30 upon which it is carried, by sliding it out ofclamps 32 or other desired means for attaching the circular removablereel 14 to the rotary hub member 30. Then, as shown in FIG. 3, reel 14may be placed horizontally about a band saw 34, which is adapted topivot downwardly to bring the band saw blade into support 36, whichcomprises a pair of plates as shown, with the band saw blade 38 fittingbetween the plates. The various fiber bundles may be separated from anannular assembly 18 by simply placing the annular assembly on top ofsupport 36, for desired positioning, and bringing down the band saw 34,for sequential cutting of the various bundles apart.

Prior to this rough cutting step, a flexible, paper sheet 40, which ispreferably made of polypropylene paper, is wrapped about the section ofthe annular assembly which is about to be cut away to form an individualbundle 42 of fibers. As shown, sheet 40 may desirably be about 11 incheswide at dimension 44 and about 15 inches long at dimension 46, for thespecific wrapping of bundles of a normal size for use in generallyconventionally sized capillary fiber dialyzer housings.

Paper sheet 40 is wrapped in a coil around bundle 42, as shown in FIG.3, so that its inner end 48 which is positioned against the bundle 42,is the end as shown which is of rectilinear shape, with a pair of 90°angle corners 50. Outer end portion 52, which is opposed to the innerend 48, defines sides 54 which taper inwardly toward outer end 56, sothat the width of outer end 56 is preferably less than half the width ofinner end 48, and preferably about 20 to 40 percent of the width ofinner end 48.

Marker means 58 are positioned on the flexible sheet, being spaced fromthe middle of the sheet toward outer end 56. In the specific embodimentshown, marker means 58 is simply a hole in sheet 40, which can bepunched simultaneously with the cutting of the sheets to shape. However,ink markings or other indicia can also be used as desired.

The purpose of the marker means 58 is to serve as an indicator of thecompression of the wrapped bundle, so that the compression may bepredetermined in the wrapping process by placing the outer end 56 of thewrapped sheet on the marker means. This is accomplished by beginning towrap sheet 40 about annular assembly 18, starting with inner end 48, andcoiling the sheet about the annular assembly 18 as shown. The taperingsides 54 facilitate the coiling and compressive narrowing of the coiledsheet 40, to place pressure upon bundle 42 by tightening the coil untilthe outer end 56 of coil sheet 40 overlies the marker means 58 as shownin FIG. 5. At this point, the bundle 42 is under a predeterminedcompressive pressure produced by sheet 40, which is essentially uniformfrom time to time, assuming that the winding conditions are kept thesame, and that the same size and shape of sheet 40 is used in everycase. The desired amount of compression is controlled by placement ofthe indicator means 58. The wound configuration may be retained by asimple piece of tape 60.

After this has been done, the previously described rough cut may be madeoutside of the edges 62 of paper sheet 40 by means of band saw 30, toseparate bundle 42 from the remainder of the annular assembly 18.Thereafter, a fine cut may be made with a blade 64 or other means asdesired, for example, a rotating band blade, cutting the bundle withinthe edge 62 of wrapped paper sheet 40, as shown in FIG. 6. Thecompressive pressure of sheet 40 provides improvement in the fine cut ofthe bundle.

The wrapped bundles may then be cleaned by washing in a solvent such asFreon type fluorochlorocarbon solvent, to remove any solvent such asisopropyl myristate which may be in the bores of the tubing. When sheet40 is made of polypropylene paper, it resists degradation by the Freonsolvent.

After drying, the wrapped bundles may be passed into the open end of atubular housing 64, after which the paper wrapping may be pulled out,leaving the fibers intact in the housing 64. The ends of the bundle 42in housing 64 may then be conventionally potted and otherwise treated inaccordance with known techniques, following which conventional end caps66 may be installed to provide a dialyzer as shown in FIG. 7.

The above has been offered for illustrative purposes only, and is notintended to limit the invention of this application, which is as definedin the claims below.

That which is claimed is:
 1. A bundle of tubular capillary fibers ofsemipermeable membrane material, said bundle being wrapped in a coil offlexible sheet, said sheet defining an inner coiled end portionpositioned adjacent said bundle, said inner coiled end portion being ofsubstantially rectangular shape, an outer end portion, opposed to saidinner end portion, defining an outer end and sides which tapertransversely inwardly toward the outer end, and marker means on saidpaper sheet spaced from the middle of said sheet toward said outer end,the outer end of said wrapped sheet overlying said marker means, saidbundle being of a predetermined compression by said coil of sheet,governed by the positioning of said marker means.
 2. The bundle of claim1 in which said sheet is made of polypropylene paper.
 3. The bundle ofclaim 1 in which said strands of capillary fibers in said bundle arearranged in generally non-parallel, crossing arrangement with adjacentstrands.